This invention relates generally to portable data collection and processing terminals for use in a Radio Frequency (RF) communication network, and, more specifically to portable terminals supporting a variety of RF transceivers and associated antenna systems. Additionally, this invention relates to methods in which a portable terminal gains access to the RF communication network.
In particular, portable data processing terminals have taken on an increasingly significant role in business environments. For example, battery powered, hand-held data collection terminals are used extensively for inventory control in warehousing and merchandising operations. Other uses of such terminals include invoicing, delivery route management, order taking and return control operations—as might be found in automobile rental operations.
In many business environments, portable data processing terminals often need to communicate in real-time with other portable terminals, peripheral devices, work stations, and host computers. To meet such communication needs, a variety of mixed hard-wired and wireless communication networks with associated communication protocols have been developed, each addressing the specific requirements of a given business environment. In the process of such development, portable terminals have undergone tailoring of both hardware and software to fully support a specific communication network and associated protocol.
As a result of such tailoring, each type of portable data collection terminal is generally capable of operating in a single type of business environment. Tailoring also results in unreasonable additional costs associated with developing, manufacturing, documenting, etc., each variety of portable data collection terminals.
More specifically, each portable data collection terminal includes a built-in radio transceiver. The built-in transceiver operates pursuant to one of a variety of types of RF (Radio Frequency) communication characteristics, characteristics that are directed per FCC (Federal Communication Commission) specification.
The choice of the type of radio transceiver, i.e., the type of RF communication characteristics, to build-in is based on the nature of the business application. For example, a digital cellular radio might be chosen in a environment having great distances between the radio and the destination transceiver. Similarly, data might be exchanged using a single channel UHF (Ultra-High Frequency), direct-sequence spread-spectrum, or frequency-hopping spread-spectrum band. Each of these bands has particular characteristics which make it attractive to a given business environment, and each generally requires a different transceiver.
After choosing the appropriate radio transceiver, an appropriate antenna is also selected. Each type of transceiver often requires a different type of antenna based on the corresponding RF communication characteristics, the shape of the portable terminal, and the business environment at issue.
Thus, there is need to provide a portable data collection terminal capable of easily supporting any of a plurality of types of radio transceivers and associated antennas, minimizing needed modifications to the terminal's hardware and software design.
As technical miniaturization has developed in the electronics industry, computers have been designed with smaller parts, and smaller peripherals. Entire peripherals have been incorporated into modules that connect to the computer. By incorporating functions into modules, computers have been designed with only basic functions, thus making the computer smaller, more efficient, and requiring less power. Custom and application-specific functions have thus been incorporated into the modules to be connected to the computer.
Modules have become so common that standards have been implemented to insure compatibility between modules and computers. The most popular of these standards is the Personal Computer Memory Card International Association (PCMCIA) standard, which sets forth a number of roughly credit card sized module configurations for use in various computers. These cards have become so popular that most portable computers are equipped with at least one PCMCIA card slot.
Modular cards can be used in a great variety of ways. PCMCIA cards may contain additional memory or storage, or implement communications or other peripheral functions. Communications supported by computer modules may include wired connection, such as over phone lines for a modem or through a wired local area network (LAN), and wireless communication such as a wireless LAN, a wide area network (WAN), or infrared. However, the number of peripheral functions that can be implemented with a single computer device has been limited in the prior art by the number of module slots supported by the computer. For example, a computer with only one card slot can only implement one peripheral function at a time. Even a computer device with more than one card slot is limited in its implementation of multiple peripheral functions. Interfacing between peripheral functions can only be done within the computer device itself, not by the card modules, since they are plugged into completely different slots and therefore are not directly interfaced together. Even when the computer accommodates interfacing between two different cards, additional processor power is required from the computer device, which is undesirable in many portable applications. Therefore, there is a need for a multipurpose computer module that can provide more than one peripheral function and control switching between those functions in a single module.
In addition, to support real-time access to a communication network, each portable data collection terminal needs to establish and maintain radio connectivity to the network. However, portable terminals must also address conflicting concerns of battery power conservation, i.e., maintaining connectivity places a substantial load on battery power. Moreover, the mobile nature of portable terminals also presents difficulties in maintaining connectivity. It would therefore be desirable to implement communication protocol techniques which address power saving and mobility concerns while providing virtually real-time access to the communication link.